This invention relates generally to the communication art and, more particularly, to an apparatus and method for selecting one of a plurality of communication channels in response to a preselected signal thereon.
In a variety of circumstances, it is desirable to selectively couple an operative circuit to one of a plurality of communication channels. For example, microprocessors have been connected to a number of inputs for the purpose of selectively measuring and recording the values of the inputs. In some cases, connection has been accomplished with a MOSFET analog switch or other device designed to selectively pass signals to the microprocessor. The particular input from which signals are passed is chosen by a control signal applied to the switch. Analog switches are also suitable for selection between a plurality of microphone lines in a recording studio. As far as applicants are aware, the above-described MOSFET analog switches have been designed and used strictly for transmission of signals in one direction.
A number of automatic dialers have been proposed for use in telephone systems. The most common such devices are designed to dial a single number. They are typically connected to a single telephone line and are activated either by a telephone switch hook or by a button or switch associated with the dialer. Each telephone line in a system must then have a separate dialer. Another automatic dialing system of which applicants are aware is designed specifically for use with a plurality of telephone lines. In this system, monitoring circuits are provided on the lines for activation by a caller to trigger automatic dialing. When one of the monitoring circuits is activated, it calls up a single number dialer associated with the system. However, the system requires a separate monitoring circuit on each line and therefore is rather costly and inflexible in its application. The system also tends to be slow in operation because the monitor must call up the dialer before the desired number can be dialed.
Therefore, in many applications it is desirable to provide an apparatus for satisfactorily coupling an operative circuit to a plurality of different communication channels. Such an apparatus is particularly desirable in the field of telephone dialing systems.